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Core flexibility of a truncated metazoan mitochondrial tRNA.

Frazer-Abel AA, Hagerman PJ - Nucleic Acids Res. (2008)

Bottom Line: Thus, the absence of canonical TpsiC-D interactions likely results in greater dispersion of anticodon-acceptor interstem angle than for canonical tRNAs.To test this hypothesis, we have assessed the dispersion of the anticodon-acceptor angle for bovine mtRNA(Ser)(AGY), which lacks the canonical D arm and is thus incapable of forming stabilizing interarm interactions.These results suggest that increased flexibility, in addition to a more open interstem angle, would allow both noncanonical and canonical mtRNAs to utilize the same protein synthetic apparatus.

View Article: PubMed Central - PubMed

Affiliation: National Jewish Health, Denver, CO 80206, USA.

ABSTRACT
Secondary and tertiary structures of tRNAs are remarkably preserved from bacteria to humans, the notable exception being the mitochondrial (m) tRNAs of metazoans, which often deviate substantially from the canonical cloverleaf (secondary) or 'L'-shaped (tertiary) structure. Many metazoan mtRNAs lack either the TpsiC (T) or dihydrouridine (D) loops of the canonical cloverleaf, which are known to confer structural rigidity to the folded structure. Thus, the absence of canonical TpsiC-D interactions likely results in greater dispersion of anticodon-acceptor interstem angle than for canonical tRNAs. To test this hypothesis, we have assessed the dispersion of the anticodon-acceptor angle for bovine mtRNA(Ser)(AGY), which lacks the canonical D arm and is thus incapable of forming stabilizing interarm interactions. Using the method of transient electric birefringence (TEB), and by changing the helical torsion angle between a core mtRNA bend and a second bend of known angle/rigidity, we have demonstrated that the core of mtRNA(Ser)(AGY) has substantially greater flexibility than its well-characterized canonical counterpart, yeast cytoplasmic tRNA(Phe). These results suggest that increased flexibility, in addition to a more open interstem angle, would allow both noncanonical and canonical mtRNAs to utilize the same protein synthetic apparatus.

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Secondary and tertiary structure of one canonical and one non-canonical tRNA. Ribbons represent phosphate backbone of: yeast cytoplasmic (c) tRNAPhe from Holbrook et al. (16), bovine mtRNASer(AGY) from Steinberg et al. (24), and S. Steinberg (personal communication).
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Figure 1: Secondary and tertiary structure of one canonical and one non-canonical tRNA. Ribbons represent phosphate backbone of: yeast cytoplasmic (c) tRNAPhe from Holbrook et al. (16), bovine mtRNASer(AGY) from Steinberg et al. (24), and S. Steinberg (personal communication).

Mentions: To address the issue of core flexibility for a variant tRNA, we have used the method of transient electric birefringence (TEB), in combination with a series of phased tRNA–A5 bulge constructs (5), to demonstrate that the noncanonical bovine mtRNASer(AGY) (Figure 1) possesses substantially more flexibility then its canonical tRNA counterparts. The current work should lead to a better understanding of the interplay between tertiary RNA structure and dynamic flexibility, and suggests that tRNA flexibility, in addition to flexibility within the ribosome, may play a role in the transit of noncanonical tRNAs during the translation cycle. Moreover, the presence of flexibility may broaden the scope of the study of the pathogenic mechanisms of point mutations within these noncanonical tRNAs (7).Figure 1.


Core flexibility of a truncated metazoan mitochondrial tRNA.

Frazer-Abel AA, Hagerman PJ - Nucleic Acids Res. (2008)

Secondary and tertiary structure of one canonical and one non-canonical tRNA. Ribbons represent phosphate backbone of: yeast cytoplasmic (c) tRNAPhe from Holbrook et al. (16), bovine mtRNASer(AGY) from Steinberg et al. (24), and S. Steinberg (personal communication).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2553581&req=5

Figure 1: Secondary and tertiary structure of one canonical and one non-canonical tRNA. Ribbons represent phosphate backbone of: yeast cytoplasmic (c) tRNAPhe from Holbrook et al. (16), bovine mtRNASer(AGY) from Steinberg et al. (24), and S. Steinberg (personal communication).
Mentions: To address the issue of core flexibility for a variant tRNA, we have used the method of transient electric birefringence (TEB), in combination with a series of phased tRNA–A5 bulge constructs (5), to demonstrate that the noncanonical bovine mtRNASer(AGY) (Figure 1) possesses substantially more flexibility then its canonical tRNA counterparts. The current work should lead to a better understanding of the interplay between tertiary RNA structure and dynamic flexibility, and suggests that tRNA flexibility, in addition to flexibility within the ribosome, may play a role in the transit of noncanonical tRNAs during the translation cycle. Moreover, the presence of flexibility may broaden the scope of the study of the pathogenic mechanisms of point mutations within these noncanonical tRNAs (7).Figure 1.

Bottom Line: Thus, the absence of canonical TpsiC-D interactions likely results in greater dispersion of anticodon-acceptor interstem angle than for canonical tRNAs.To test this hypothesis, we have assessed the dispersion of the anticodon-acceptor angle for bovine mtRNA(Ser)(AGY), which lacks the canonical D arm and is thus incapable of forming stabilizing interarm interactions.These results suggest that increased flexibility, in addition to a more open interstem angle, would allow both noncanonical and canonical mtRNAs to utilize the same protein synthetic apparatus.

View Article: PubMed Central - PubMed

Affiliation: National Jewish Health, Denver, CO 80206, USA.

ABSTRACT
Secondary and tertiary structures of tRNAs are remarkably preserved from bacteria to humans, the notable exception being the mitochondrial (m) tRNAs of metazoans, which often deviate substantially from the canonical cloverleaf (secondary) or 'L'-shaped (tertiary) structure. Many metazoan mtRNAs lack either the TpsiC (T) or dihydrouridine (D) loops of the canonical cloverleaf, which are known to confer structural rigidity to the folded structure. Thus, the absence of canonical TpsiC-D interactions likely results in greater dispersion of anticodon-acceptor interstem angle than for canonical tRNAs. To test this hypothesis, we have assessed the dispersion of the anticodon-acceptor angle for bovine mtRNA(Ser)(AGY), which lacks the canonical D arm and is thus incapable of forming stabilizing interarm interactions. Using the method of transient electric birefringence (TEB), and by changing the helical torsion angle between a core mtRNA bend and a second bend of known angle/rigidity, we have demonstrated that the core of mtRNA(Ser)(AGY) has substantially greater flexibility than its well-characterized canonical counterpart, yeast cytoplasmic tRNA(Phe). These results suggest that increased flexibility, in addition to a more open interstem angle, would allow both noncanonical and canonical mtRNAs to utilize the same protein synthetic apparatus.

Show MeSH
Related in: MedlinePlus